1. Field of the Invention
The present invention relates to a paper feed cassette to be used in feeding a recording medium in an image formation device, a recording medium size detector for detecting the size of the recording medium loaded on the paper feed cassette, and an image formation device comprising this recording medium size detector.
2. Description of the Background Art
In image formation devices such as a copy machine or printer, there are types where the paper feed cassette having a recording medium loaded thereon is installed in a body case, the recording medium loaded on a paper feed cassette is fed, and image is formed on such recording medium. This kind of paper feed cassette comprises a side fence abut on the end fence in the width direction orthogonal to the feeding direction of the recording medium loaded on this cassette body, and an end fence abut on the rear end face in the feeding direction of the recording medium loaded on this cassette body, and the loading position of the recording medium is determined by sliding the side fence and end fence and abutting them on the recording medium.
Further, in an image formation device employing a paper feed cassette comprising such a slidable side fence and end fence, there is a type which comprises a mechanism for detecting the size of the recording medium loaded on the paper feed cassette from the slide position of the side fence and end fence (e.g., this is disclosed in the gazettes of Japanese Patent Laid-Open Publication No. 2000-118729 and Japanese Patent Laid-Open Publication No. H6-32489).
In the invention disclosed in foregoing Japanese Patent Laid-Open Publication No. 2000-118729, a measurement piece which slides in synchronization with the movement of the side fence, and a portion to be measured that rotates or slides in synchronization with the movement of the end fence are provided to the paper feed cassette. First and second ranging means positioned so as to face the measuring piece/portion to be measured when the paper feed cassette is installed in the case body are provided to the body case of the image formation device to which the paper feed cassette is installed. As a result of the measuring piece sliding in synchronization with the movement of the side fence, and the portion to be measured rotating or sliding in synchronization with the movement of the end fence, the distance between the measuring piece and first ranging means, and the distance between the measure portion and second ranging means upon installing the paper feed cassette in the body case will change. By detecting these distances with the first and second ranging means, the slide position of the side fence and end fence; that is, the size of the recording medium loaded on the paper feed cassette can be detected.
Further, in the invention disclosed in foregoing Japanese Patent Laid-Open Publication No. H6-32489, a paper sheet size recognition member that rises and falls in synchronization with the movement of a guide member (side fence), and a paper sheet size recognition member that rises and falls in synchronization with the movement of a guide member (end fence) are provided to the paper feed cassette. These paper size recognition members are disposed in mutually adjacent positions in close proximity. A plurality of actuators to be selectively pressed with the protruding paper sheet size recognition members is provided to the body case of the image formation device to which the paper feed cassette is installed. The paper sheet size recognition member rises or falls according to the size of the recording medium loaded on the paper feed cassette, the plurality of actuators is selectively pressed with the paper size recognition members protruding when the paper feed cassette is installed in the body case, and the size of the recording medium loaded on the paper feed cassette is detected depending on which actuator is being pressed.
Further, in the invention disclosed in foregoing Japanese Patent Laid-Open Publication No. 2000-118729, the measuring piece that slides in synchronization with the movement of the side fence and the portion to be measured that rotates or slides in synchronization with the movement of the end fence function independently upon detecting the size of the recording medium. Thus, the ranging means for measuring the distance to the measuring piece and the ranging means for measuring the distance to the portion to be measured must be provided separately.
Further, in the invention disclosed in foregoing Japanese Patent Laid-Open Publication No. H6-32489, the paper sheet size recognition member that rises and falls in synchronization with the movement of a guide member (side fence), and the paper sheet size recognition member that rises and falls in synchronization with the movement of a guide member (end fence) function independently upon detecting the size of the recording medium. Thus, two types of actuators; namely, an actuator for detecting the rising and falling state of the paper sheet size recognition member that rises and falls in synchronization with the movement of the guide member (side fence), and an actuator for detecting the rising and falling state of the paper sheet size recognition member that rises and falls in synchronization with the movement of the guide member (end fence) must be provided.